Comprehensive external audit for HDR brachytherapy systems – the national experience

On-site audits in brachytherapy are performed for all HDR units after commissioning in the Czech Republic. Air-kerma strength, source positioning accuracy, dose calculation accuracy by treatment planning system, and reconstruction algorithm in terms of geometry accuracy are verified. Results obtained in 2003 – 2018 for 24 audited HDR brachytherapy sources are described in the paper. Weak points in HDR brachytherapy process are emphasized. The audited centres often failed in good knowledge of applicators, especially of needles with different blind tip lengths. (paper)